1. Field of Invention
This invention relates generally to keyboards and more particularly to ergonomically designed keyboards for use with computers and other electronic data input devices.
2. Discussion of Prior Art
(Introduction) When keyboards were originally invented, placement of keys was directly on the front of the device. This was necessary so that fingers could strike with enough force to have levers hit the paper, resulting in printed letters on the page. The design of the machine was controlled by the mechanics necessary to make it work. When electric typewriters came about, the needed force on the keys was tremendously decreased. However, the basic keyboard format and positions of the keys has remained similar to the early formats.
Many problems have risen from the unnatural position of the shoulders, forearms, wrists, and fingers while making repetitive motions to operate the keyboard. In more recent years, computers with electronic keyboards have become commonplace in homes, schools, and businesses. With dramatically increased use has come dramatically increased cases of repetitive stress injuries. In fact, carpal tunnel syndrome (CTS) and other cumulative trauma disorders are the fastest growing category of occupational injuries in the United States. "It (CTS) is now recognized to afflict nearly two million workers . . . and with millions of schoolchildren growing up using computers, more and more jobs being done on computers, millions of adults abandoning the United States mail for E-mail, and growing numbers of people signing on to the Internet every day, there is a pressing need for preventive attention and simpler correctives.".sup.1 (Copies of all footnote references can be found in Appendix A). FNT .sup.1 Brody, Jane E., "Personal Health," New York Times, Feb. 28, 1996, p. C9.
From 1983 to 1987, job-related cumulative trauma disorders tripled. By the year 2,000, an estimated 50 percent of the work force could suffer from these repetitive stress injuries (RSIs), according to the National Institute of Occupational Safety and Health. It has become an expensive condition troublesome for both the employee and industry..sup.2 According to Design News magazine, "Many employees suffer from Carpal Tunnel Syndrome, the nation's leading cause of occupational illness, and the second most common cause of operations. The cost to employees: more than $27 billion a year..sup.3 In fact, there have been law suits in more recent years surrounding CTS. In December of 1996, a federal jury in Brooklyn awarded nearly $6 million to three women who sustained arm, wrist, and hand injuries while using keyboards made by the Digital Equipment Corporation..sup.4 FNT .sup.2 Johnson, Elaine, "Is There a Cure for Carpal Tunnel Syndrome?," Safety and Health, February, 1994, p. 34. FNT .sup.3 "Work Envelope Tackles Carpal Tunnel Syndrome," Design News, Nov. 1, 1993, p. 44. FNT .sup.4 "Big Jury Award in Injury Case Over Keyboards," New York Times, Dec. 10, 1996, p. D1.
(Identification of Problem Areas) CTS is caused by compression of the median nerve at the wrist within the carpal tunnel..sup.5 The cause of carpal tunnel syndrome in relation to frequent use of a conventional keyboard can be broken down into three problem areas, (1) the wrists, (2) the fingers, and (3) the forearms. Besides CTS, other repetitive stress injuries can show up in (4) the shoulder and neck area. FNT .sup.5 Steyers, Curtis M., MD, "Practical Management of CTS," The Physical and Sportsmedicine, Vol. 23, January, 1995, p. 84.
(Problem Areas--(1) Wrists) The most obvious problem is the wrists. With the conventional keyboard, the operator must both pronate his/her wrists to a horizontal plane and angle them inward with palms down and fingers aligned with the straight rows of keys. When operating outside of their natural and ideal range, tendons and nerves are adversely affected, and over time, can lead to CTS. Also, when the operator instinctively rests his/her arms due to lapses in his/her work, or fatigue, he/she will rest them directly on the wrist, further putting pressure on the median nerve.
(Problem Areas--(2) Fingers) Secondly, the finger placement and movement play an important role. With the straight lines of keys on a conventional keyboard, the varying length of fingers is not taken into consideration. Longer fingers are caused to be held in an arch, while shorter fingers lie flatter and even require the operator to move the entire arm forward or backward to reach keys on the upper and lower rows. In a natural position, the fingertips form a curve shape. But they are forced into a straight line or rows on the conventional keyboard.
The pinky fingers are used to reach many frequently-used keys such as the backspace, escape, control key, and alt key. This creates excessive sideways twisting movements of the wrists.
Also, the natural pushing motion for the fingertips is at an angle downward and inward toward the operator. However, the conventional keyboard requires a straight downward motion on the home keys, the downward/inward motion for the closest row of keys, and the opposite motion, upward/outward, for a majority of the keys, those above the home row. Not only do the unnatural motions cause stress on the muscles and tendons, but the constant changing of directions of motion causes additional stress.
(Problem Area--(3) Forearms) The third area affecting CTS is the position of the forearms. With the conventional keyboard, the arms may be held even with or higher than the elbows. This creates considerable strain when an operator must use the keyboard for long periods of time. If the hands are held lower than the elbows, such as putting the keyboard on the lap, muscles on the top of the forearm must work harder to keep the fingers raised up into position. Again, the tendency is for the operator to rest his/her wrists, causing pressure on the carpal tunnel.
(Problem Area--(4) Shoulders/Neck) Besides CTS, other RSIs can arise from the unnatural position of the shoulder joints. While using a conventional keyboard, they are rotated slightly forward and often bear the weight of the arms for long periods of time. The natural position of the shoulders is when the elbows are down by the operator's sides. Muscle strain in the shoulders/neck area and subsequent headaches can be caused by the unnatural forward and inward rotated position of the shoulders necessary for the operation of the conventional keyboard.
(Introduction to Prior Art) When key mechanisms advanced from mechanical to electronic, the shape of the keyboard could be made to fit the operator's needs, instead of being dictated by the mechanics of the device. A number of prior art keyboard designs have been proposed to improve one or more of the factors contributing to CTS and other repetitive stress injuries. (Copies of all prior art referenced can be found in Appendix B).
(Prior Art--Wrists) Many designs proposed separating the keyboard into left-hand and right-hand components. For example, FIG. 3 of U.S. Pat. No. 4,661,005, by Lahr, (issued Apr. 28, 1987) shows a keyboard which slides apart from the middle, causing the hands to separate, thus straightening the inward angle of the wrists. Other methods for straightening the wrists involved simply splitting the keyboard between the left-hand and right-hand keys, and angling the edge of the keyboard next to the operator at an outward angle. This can be seen in U.S. Pat. No. 362,434 (FIG. 8) by Abell et al. (issued Sep. 19, 1995), U.S. Pat. No. 5,424,728 (FIG. 1) by Goldstein (issued Jun. 13, 1995), and U.S. Pat. No. 5,612,691 (FIG. 2) by Murmann and Frank (issued Mar. 18, 1997). This same idea is shown in U.S. Pat. No. 5,129,747 (FIG. 1) by Hutchison (issued Jul. 14, 1992), which angles the keyboard into a V shape or chevron design to allow for straightening of the inward wrist angle. Similarly, a rounded V or wave shape has been proposed as illustrated by U.S. Pat. No. 5,360,280 (FIG. 1) issued to Camacho and Granadino (Nov. 1, 1994). These inventions, however, provide only a partial solution and do not correct the many other factors contributing to the repetitive stress injuries with keyboard use.
One of these other factors is the twisting of the wrists into a horizontal planar, unnatural position (pronation). Rollason, U.S. Pat. No. 5,029,260 (FIG. 1) (issued Jul. 2, 1991), proposed a keyboard which forms a large arch, allowing the hands to tilt slightly outward. Other designs proposed keyboards higher in the middle than on the left and right ends, as shown in U.S. Pat. No. 5,339,097 by Grant (issued Aug. 16, 1994), and U.S. Pat. No. 323,817 by Buchin (issued Feb. 11, 1992).
U.S. Pat. No. 362,432 (FIGS. 2,3) by Paull et al. (issued Sep. 19, 1995), combines attempts to correct both the inward angle and pronation problems of the wrists by providing a wave shape housing which is also raised in the middle between the hands. This design, however, lends itself to having the operator rest his/her wrists directly on the keyboard housing, which puts pressure on the carpal tunnel, and therefore on the median nerve, increasing the likelihood of injury.
U.S. Pat. No. 5,137,384 (FIG. 1) to Spencer and Albert (issued Aug. 11, 1992), sets up two completely vertical keyboard halves, allowing the weight of the extended hand/forearm to be borne comfortably on the narrow side of the hand opposite the thumb, but overcorrects the pronation past the natural wrist position.
Spencer's device also neglects the natural grasping and striking force of the fingers. By mounting the keys to face left and right, the user's fingers are forced to strike in an unnatural direction. Also, the flat keyboard surface causes extra strain on the user's fingers because a flat surface does not accommodate for differences in finger length. To help overcome this problem, the user would tend to tip his/her fingers outward and wrists inward so that the tips of the fingers are even, or may continually adjust the position of the wrist during data entry to accommodate for short and long fingers. Both of these scenarios would further increase strain on the wrist, forearms, and tendons of the fingers because of the unnatural angle created at the wrist between the top of the hand and the forearm.
Like Spencer, Mohler, U.S. Pat. No. 5,160,919 issued November 1992, presented a vertical keyboard. The keys are on opposite sides of a vertical base, with "palms facing each other." Again, this design does not correct the problem of the user's fingers being required to strike in an unnatural direction, nor does it accommodate for differences in finger length. In another embodiment of Mohler's invention, the edge of the keyboard areas farthest away from the user is made to angle outward so that the keys are visible (described in Col. 4, lines 25-28). This creates a problem at the wrist by causing an angle between the top of the hand and the forearm, therefore putting great strain on the wrists, forearms, and tendons of the fingers during data entry.
Lo provides for the vertical formation ("upright stack") of the operator's fingers on a mouse device (U.S. Pat. No. 5,576,733) in order to correct problems associated with the wrist. His design, however, applies only to the use of a mouse and requires that the weight of the hand, forearm, and the device, repetitively be borne by the arms and shoulders when the operator picks up and moves the mouse, as is frequently necessary during its use.
Danziger, U.S. Pat. No. 5,426,449 (issued Jun. 20, 1995) attacks the same wrist deviations with his "pyramid shaped ergonomic keyboard," (FIG. 1) and also provides attachable devices for the resting of the hands and arms (FIGS. 7a and 7b). However, there are a number of flaws with Danziger's design. The housing unit is of a complex nature, being split into three sections, with adjustable left and right sides of the pyramid (FIGS. 3, 3a, 5b, 5c), flip-out hand rests (FIG. 3), and bulky arm attachments (FIGS. 7a, 7b). This makes it impractical for convenient individual use or for business to manufacture. The placement of the often-used backspace key is not in the usual position as that of a conventional keyboard (FIG. 4a). Also, the function keys on the front, center portion are not in the same general configuration or placement as that on a conventional keyboard (FIG. 4a). Ample relearning time would be needed for the operator to become familiar with the new placement of many keys. While the structure does provide for a more natural wrist position, the concave nature of the two side panels of keys (FIG. 2) requires that the fingers be raised even higher than that of a conventional keyboard to make reaches both up and down from the home row of keys. This causes repeated strain on the flexor and extensor tendons of the fingers.
(Prior Art--Fingers) Other keyboard inventors have also proposed concave keypad structures, possibly in an attempt to accommodate the differences in the lengths of the fingers. This is shown in U.S. Pat. No. 4,597,681 (FIG. 1) by Hodges (issued Jul. 1, 1986), U.S. Pat. No. 5,731,808 (FIG. 1) by Gaither (issued Mar. 24, 1998), U.S. Pat. No. 5,689,253 (FIG. 1) by Hargreaves and Lunde (issued Nov. 18, 1997), and U.S. Pat. No. 5,775,822 (FIG. 2) by Cheng (issued Jul. 7, 1998). Again, this concave design requires extra, unnatural movement of the fingers.
FIG. 2 of Mensick's "Ergonomically Improved Standard Keyboard," (U.S. Pat. No. 5,716,149, issued Feb. 10, 1998) shows the keyboard plane flat rather than concave, and keys somewhat staggered out of the normal horizontal rows " . . . based upon consideration of the relative positions of the bases of the fingers . . . and the natural orientation of the fingertips." Similarly, as shown in FIG. 4 of Miller's U.S. Pat. No. 5,660,488 (issued Aug. 26, 1997) a flat planar surface is used for the keys, but each row arches to fit the curve formed by the fingertips when held in a natural position.
As stated earlier, overuse and twisting wrist motions come from the pinky fingers being used for many frequently-used keys. This has caused keyboard inventors to give these reaches to other fingers. This can be seen in U.S. Pat. No. 5,156,475 (FIG. 5) by Zilberman (issued Oct. 20, 1992) which shows an inverted T-shape key in the middle of the keyboard that includes the enter function, Danziger's design discussed earlier (U.S. Pat. No. 5,426,449 issued Jun. 20, 1995) which provides an entire front thumb panel (FIG. 3), U.S. Pat. No. 5,711,624 (FIG. 2) (issued Jan. 27, 1998) by Klauber and U.S. Pat. No. 5,620,267 (FIG. 2) also by Klauber (issued Apr. 15, 1997), which provide for a thumb-activated backspace/erase key located on the left half of the conventional spacebar, and a thumb-activated control key.
Only Gandre (U.S. Pat. No. 5,767,463 issued Jun. 16, 1998) has recognized that the force of the fingertips, when held in a natural position, is downward and inward, toward the operator. FIG. 5 of his design shows a front-facing keyboard which has rows of keys each individually angled at a 45.degree. slant away from the user (FIG. 4), coming up from the support base. When struck, the keys slide downward and inward toward the user. His design, however, does not provide for wrist and forearm correction, nor does it correct reaches to allow for any differences in finger lengths or curvature.
(Prior Art--Forearms) Fifteen of the thirty-five muscles which move the hand are in the forearm rather than the hand itself..sup.6 Therefore, it is very important that any ergonomic keyboard correct for muscle and tendon strain in this area. Most previous inventions have failed to correct the strain on the flexor and extensor tendons associated with the forearm because the fingers are held even with or above the horizontal plane of the forearms, and then must be picked up to make reaches above the home row. The inclination of the keyboard operator to help relieve this stress is to rest the keyboard on his/her lap. Rollason's arching convex curved surface keyboard design described earlier (U.S. Pat. No. 5,029,260 issued Jul. 2, 1991) provides for a support to position the structure over the operator's legs on his/her lap (FIG. 2). However, his correction of the pronation problem is offset by the creation of a new problem when the keyboard is put on the lap, namely the additional stress put on the wrist when the forearm angles down and the wrist angles up. Danziger's design, also discussed earlier, (U.S. Pat. No. 5,426,449 issued Jun. 20, 1995) mentions that "the pyramid-shaped keyboard may be used while resting in the lap of the operator." As with Rollason's, this design doesn't allow for the new angle created with the forearm and wrist, when the device is rested on the lap. FNT .sup.6 "Hand," The World Book Encyclopedia, 1990, Vol. H, p. 39.
Vulk's patent (U.S. Pat. No. 5,892,499 issued April 1999) focuses on correcting the problem of strain on the wrists and forearms. He proposes a palm and forearm support device which basically eliminates the angle created between the forearm and top of the hand. However, his device provides only a partial solution because the top of the operator's wrists are forced to face up, unnaturally rotating them into a horizontal plane or pronated position (FIGS. 5, 10, 15, 20, 21, 23, 27, and 31).
(Prior Art--Neck/Shoulders) Keyboards which split the left-hand and right-hand sections and place them at shoulder width, promote a more natural position and thus less shoulder and neck strain. Keyboards designed for use on the operator's lap have promoted a much more natural arm and shoulder position, but previous designs have not taken into consideration the new downward angle created and where the weight of the arms will rest.
Neck strain can be caused by a repetitive motion of the operator to look up and down. As angles of the keys or sections of the keys have been changed in many ways to accommodate natural motion, designers have struggled with ways for the operator to still view the keys. Spencer, for example (U.S. Pat. No. 5,137,384 issued Aug. 11, 1992 and discussed earlier), devised angled mirrors for the operator to read the keys (FIG. 5). However, repetitive stress injuries strike mainly those who have been taught and consistently use the touch method for typing (striking keys from the memorized reach of fingers without looking for them). For that reason, it is not necessary for keyboards which are designed for preventing RSIs to allow full view of the frequently-used keys. In fact, when the keys are in full view, a person learning the most efficient way to use a keyboard (the touch method), finds it very difficult to learn not to consistently look down for the keys. If this habit is created, it promotes a much greater risk of muscle strain and injury to the neck and shoulders.
(Prior Art--Conclusion) While many previously-proposed keyboards may improve one or more problem areas, none is comprehensive enough to improve all of them at once. Therefore, it is most desirable to provide a keyboard which takes into account all of the above-mentioned repetitive motion problem areas. Furthermore, there remains a need in the art for a keyboard which minimizes the strain and injuries to the operator without him/her having to undergo extensive retraining.